Sperm cells are the male gametes in animals and plants that fertilize female gametes (ova) to produce offspring. Male mammals produce spermatozoa in their testicles, which are stored in the epididymis until they mature. When ejaculation occurs, these sperm travel through the vas deferens to the prostate gland where they mix with seminal fluid secreted by the seminal vesicles and other glands to form semen. The urethra then carries this semen out of the body through the penis.
The average human male produces about 400 million spermatozoa per day which is about 17 billion per year. Each individual sperm cell is extremely small, typically only 5 micrometers long (0.005 mm). Despite their size, sperm cells contain a large amount of genetic material – approximately 3 billion base pairs of DNA packaged into 22 chromosomes plus an X or Y chromosome that determines gender. This makes them one of the densest information storage organs known.
The function of spermatozoa is to deliver this DNA to a ovum so that it can be used in combination with the ovum’s own DNA to create a new organism during sexual reproduction. In order for fertilization to occur, successful transport of both egg and sperm cells is required as well as precise interactions between them at multiple levels including chemical, physical and electrical signaling. If any of these steps fail then fertilization will not take place.
Once inside the female reproductive tract, sperm must first find their way to the vicinity of an ovum (this process is called capacitation). They do this by swimming up through the cervix and uterus using a series of intricate movement patterns powered by their flagella tail structures. During this journey they also undergo further changes that prepare them for fertilization including release of enzymes that allow them to penetrate any protective layers around the ovum known as cumulus oophorus and zona pellucida . Once they reach the eggs, another series of complex interactions occur leading eventually to penetration of the egg cell membrane by a single sperm – after which point fusion of egg and sperm nuclei takes place and meiosis can begin resulting in formation of a zygote with half- paternal/half-maternal chromosomes . From here normal embryonic development can proceed leading ultimately to birth of a new individual..
Anatomy Of A Sperm Cell
All eukaryotic cells contain mitochondria within their cytoplasm – organelles that serve an important role in energy production via oxidative phosphorylation . Mammalian spermatozoa however are unique in possessing very few mitochondria within their tails relative to other cell types . This reduction results in ATP being produced primarily via glycolysis rather than oxidative phosphorylation which has special implications for fertility as will be discussed later on.. Each spermatocyte contains 4 round mitochondria when it enters meiotic division but following two rounds